"We've decorated her locker, bought new uniforms, even surprised her with a new backpack," Gardner wrote. "But tonight just before bed, we did another pre-middle school task that is far more important than the others."

The post has been viewed more than 650,000 times.

Gardner said she thinks other people have used this idea before, but she put it into her own words.

"I came up with the idea as I was brushing my teeth the other night," Gardner said. "I had been thinking for weeks about how my daughter was entering middle school and how I wanted to prepare her as best as I could. My toothpaste was a mess and I went to clean it and started thinking about how, just like words once you have said them, you can't put toothpaste back in a tube."

Breonna understood the metaphor, and Gardner spent some time discussing examples in her own life, she said.

"The reason lessons like this are so important to us is because, unlike most people who have their children for 18 years, we only have Breonna,11, for 9 years," Gardner said.

She explained that Breonna came into the family through foster care, after Gardner and her husband, Paul, 46, struggled with infertility.

The Gardners fostered Breonna and her sister, Bridgett, 7, for more than 500 days before adopting them last year.

"When the girls came to us, they had suffered from various forms of neglect, and we had to win their trust and love," she said.

Gardner said they are thankful for the toothpaste story going viral, but they would love to see the foster care adoption part of their story go viral, too.

"There are so many wrong messages out there about foster care, and we would love to show what a miracle foster care adoption has been for our family," Gardner said.

Gardner said Breonna went through much of her early life without someone to tell her how cherished and loved she is. Gardner said she and her husband are now making up for lost time.

"Each morning, when I go to wake up Breonna, I take a few minutes before we get busy with breakfast and rushing out the door to school to tell her how much I believe in her, how important she is to me and how valuable her life is. I know that, as she becomes a pre-teen and teenager, the world is going to tell her what to believe about herself. I want her to hear my voice first each morning telling her what I see in her and how proud I am of her."